Self-destruction device



J n- 1, 195 A. H. DELL ETAL SELF-DESTRUCTION DEVICE Filed 001:. 29, 1954 FIG.5

PROXIMH'Y FUZE INVENTORS ALBERT H. DELL JOHN H. KUCK JULES H. SREB ATTORNEYS nited States SELF-DESTRUCTION DEVICE Application October 29, 1954, Serial No. 465,757

4 Claims. (Cl. 102-70-2) The present invention relates generally to self-destruction switching mechanisms, and more particularly to an improved time delay switching mechanism for installation in an antiaircraft projectile fuze to impart selfdestructive characteristics to the fuze.

The low angle and suddenness of suicide bomber attacks in naval engagements involving large numbers of friendly warships makes it difiicult to put up a defensive barrage of antiaircraft projectiles without endangering the lives of personnel and equipment on nearby, friendly warships.

This problem becomes particular-y acute when antiaircraft projectiles are equipped with radio proximity fuzes. it is possible that a projectile of the latter type, fired at a low angle in the vicinity of friendly warships, may not explode upon its intended target but may proceed beyond the target to jeopardize friendly warships.

in order to alleviate the problem, it is necessary to provide the projectile fuze with a self-destruction switching mechanism capable of early operation. For example, the fuze mechanism should operate between six to eight seconds after firing of the projectile so that detonation will occur before the projectile can travel to within a lethal distance of friendly warships.

A self-destruction switching mechanism suitable for the purpose indicated, of course, must be compatible with the modern, electrically activated fuzes now most commonly employed and, in particular, with the radio proximity fuze. Furthermore, inasmuch as the mechanism is to be expendable, economy and simplicity of construction are important considerations. 7

It is, therefore, an object of this invention to provide a self-destruction mechanism which can be easily installed into a projectile fuzed with an electrically activated fuze and, in particular, with a radio proximity fuze, to make the projectile self-destructive after a pre determined time interval following discharge of the projectile from a gun.

Another object is to provide a self-destruction switching mechanism suitable for installation in an electrical fuze of a projectile, with the mechanism employing a switching means to initiate self-destruction, the switching means being positively held in open position until the specified time has elapsed, after which the switching means is positively held in closed position.

Other objects and many of the attendant advantages of this invention will be apparent by reference to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a side elevation of a self-destruction switching mechanism embodying this invention, said mechanism being mounted on a support, a fragment of which is here shown;

Fig. 2 is a fragmentary plan of the self-destruction switching mechanism and support shown in Fig. 1;

Fig. 3 is an end view of the self-destruction switching mechanism shown in Fig. 1;

Fig. 4 is a perspective of one element utilized in the atent self-destruction switching mechanism of the invention; and

Fig. 5 is a circuit diagram illustrating the manner in which the self-destruction switching mechanism is incorporated in a radio proximity fuze.

In accordance with the invention, an electrically operated projectile fuze, having a source of electrical energy and an explosive primer connectable across said source, is provided in combination with a self-destruction switching mechanism.

This switching mechanism includes a thermal squib ignitable by the source of electrical energy and a heat conductive pin associated with the squib to receive heat therefrom. The mechanism further includes a stationary contact which is located in heat conductive association with the squib. The contact is electrically connected to the source of electrical energy, and it also holds a slug of fusible material.

A switch arm is connected to the primer and initially held to the pin by a fusible material. This switch arm is arranged to be moved into engagement with the contact to connect the primer across the source of electrical energy when the slug and the fusible material on the pin are melted by heat produced by the squib when ignited.

Reference is now made in more detail to Figs. 1, 2, and 3 of the drawings, in order to describe the selfdestruction switching mechanism for incorporation in an electrically operated fuze. In these figures there is shown a support 11 mounting a thermal squib 12, that is, a slow burning, heat producing squib which is nonexplosive. The igniting element normally incorporated in squ ibs of this type is electrically connected, as by leads 13, to a potential source of energy such as a deferred action battery conventionally employed in radio proximity fuzes.

In brief, a deferred action battery is one in which the electrolyte is contained in an ampule and thus retained out of contact with the electrodes until the ampule is bro-ken by the force of setback upon firing of the projectile carrying the battery. Distribution of the electrolyte is largely affected by centrifugal force created by projectile Sp1l'1.

A heat conductive pin 14, of stepped configuration, and having a tip 15 is mounted in one end of the squib 12 to receive and conduct heat developed by the squib 12. The pin 14 is formed with a substantially ninety-degree bend at approximately its midpoint and projects freely through an aperture 9 in the support 11.

A movable switch arm 16, in the form of a length of spring wire, has one end 7, as seen best in Fig. 3, secured to the support 11 at a point remote from the tip 15 of the conductive pin 14. The free end 17 of the switch arm 16 is initially fixed to the tip 15 of the pin 14 by solder 18. A weight 19, attached to an intermediate portion of the switch arm 16, provides motivation for the arm 16 under centrifugal force when the free end 17 is released in a manner to be described hereinafter. The switch arm 16 is electrically connected by a lead 21 to a primer, the detonation initiating component of a radio proximity fuze 35, shown in Fig. 5.

An arcuate saddle 22, best seen in Fig. 4, comprises a semi-cylindrical shell 23 of electrically conductive material having a tangential projection 24 extending from one side thereof. The projection 24 is cut away at one side of its free end portion to define a recess 25 forming a stationary contact 26 for receiving the free end 17 of the switch arm 16 when released from the tip 15 of the conductive pin. A mass of solder 27 is held in the recess 25.

Shell 23 partially envelopes the squib 12, with a thin layer 28 of mica or other insulating material placed between it and the squib 12. The projection 24 extends freely through an aperture 8 in the support 11 to place the stationary contact 26 on the same side of the support 11 as the tip 15 of the pin 14 and the switch arm 16. The stationary contact 26 is so positioned that it will be engaged by the free end 17 of the switch arm 16 upon release from the tip- 15 of the pin 14-.

A lead. 29 is secured, as by solder, to the shell 23, and it electrically connects the shell 23, and hence, the stationary contact 26 to the deferred action battery.

Referring now to Fig. 5, the electrical circuit of the self-destruction switching mechanism of this invention, as installed in a radio proximity fuze, is illustrated. A potential source of energy 31, in this instance a deferred action battery and primer 32, having two leads 21 and 34 for carrying the igniting current, are components of a radio proximity fuze. The remainder of the fuze is generally designated as 35, with the leads 36 electrically connecting the battery 31- and the primer 32 thereto.

The self-destruction switching mechanism is generally indicated within the dotted lines of Fig. The leads 13 from the igniting element of the squib 12, as described above, are connected across. the battery 31. A thermal circuit breaker 37, of any conventional type, is interposed in series with the igniting element of the squib 12 in order to prevent excessive discharge of the battery 31 after ignition of the squib 12. The conductive pin 14, the saddle 22, including shell 23, projection 24 and stationary contact 26, and the switch arm 16 have been described above and are readily seen within the dotted lines of Fig. 5.

The shell 23 is connected by the. lead 29 to one side of the battery 31, while one lead 34 from the primer 32 is connected to the other side of the battery 31. The other lead 21 from said primer 32 is connected to the switch arm 16, which, as already stated, has its free end: 17 soldered. to' the conductive pin 14. It should be reiterated at this stage that the saddle 22 is insulated from the squib 12 by the thin layer 28 of mica or other insulating material: thereby averting the shorting of the primer 32' across the battery 31 and the premature detonation of the primer 32.

It is preferable to design the conductive pin 14' and the saddle 22 so that the slug of solder 27' at the stationary contact 26 melts before the slug of solder 18 on the tip does. In this manner, the stationary contact 26 is prepared to receive the free end 17 of the switch arm 16 when the latter is released from the tip 15.

Having described the structure and arrangement of components of the self-destruction switching mechanism as employed with the radio proximity fuzc 35, the operation of the mechanism will now be described. When the radio proximity fuze is installed in a projectile, the ampule battery 31 is, of course, in an unenergi'zed condition. Upon firing the projectile, the electrolyte-containing ampule of the battery 31' is broken to release the electrolyte for reaction with the battery electrodes and the battery 31 is energized, thereby sending electrical power through the leads 13 to ignite thesquib 12. Heat produced by the burning of the squib 12 simultaneously travels along the conductive pin 14 towards the tip 15' and along the projection 24 of'thesaddle 22 towards the stationary contact 26.

When a sufficient quantity of heat has accumulated at the tip 15, the slug of solder 18- melts and releases the switch arm 16. Underthe influence ofcentrifugal force developed by the rotating projectile, the weight 19 moves outward from the axis of rotation of the projectile, thus causing'the switch arm- 16 to swing towards the station ary contact 26. When the free end 17 of the switch arm 16 engages the stationary contact 2 6, as shown in dotted lines in Fig. 1, it becomes immersed in molten solder from the slug 27. This slug 27, as mentioned before, is: designed to melt prior to the time of release of; the switch arm 16: The free. end 17 is immersed in a liquid conductor, that is, the molten solder. This end,

therefore, establishes a good electrical connection with the stationary contact 26. In this way, energy loss normally caused by chatter and poor engagement at contact is kept at a minimum.

It can be seen readily that upon engagement of the free end 17 of the switch arm 16 with the stationary contact 26, the primer 32 is connected directly across the battery 31 and detonation thereof occurs, to set off the radio proximity fuze 35-.

The delay time is provided by the interval required for a suflicient quantity of heat to travel along. the conductive pin 14 to melt the slug of solder 18 at the tip 15. The delay time may be varied as desired by changing the dimensions and/or configuration of the conductive pin 14. Of course, the: material. used to make the conductive pin will also determine the delay time.

If the time delay switching mechanism is not to be used under conditions wherein centrifugal force is brought to bear, for instance in a non-rotating projectile, then the switch arm 16 may be spring biased to move into engagement with the stationary contact 26. If this is the case, the weight 19 may be dispensed with.

Obviously, the self-destruction switching mechanism described above maybe applied to uses other than in explosive projectiles, wherein it is desired to close an electrical circuit after a predetermined interval has elapsed. in addition, many modifications and variations of this invention are possible in light of the foregoing teachings. Therefore, it is to be understood that within the scope of the appended claims this invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination with an electrically operated projectile fuze having. a source of electrical energy and an explosive means connectable across said electrical source, a self-destruction. switching mechanism including thermal means ignitable by said electrical source, heat conductive means associated with said thermal means to' receive heat therefrom, other means in heat conductive associattion with said thermal. means, said other heat conductive means being electrically connected to said electrical source, a first fusible material held by said"- other heat conductive means, a second fusible material, and meansincluding an arm connected to said explosive meansand initially held to said first heat conductive means by said second fusible material, a weight connected to anintermediate portion of said arm, said arm being movable, by centrifugal force, into engagement with said other heat conductive means to connect said explosive means across said electrical source when said first fusible material and said second fusible material on said first heat conductive means are melted by heat produced by said thermal means when said thermal means are'ignited.

2. In combination with an electrically operated projectile fuze having a source of electrical energy and an explosive primer connectable across said electrical source, a self-destruction switching mechanism including a thermal squib ignitable by said electricalsource, a heat conductive pin associated with said squib to receive heat therefrom, a stationary contact inheat conductive association with said squib, said contact being electrically connected to said electrical source, a slug of fusible material held by said contact, other fusible material, and a weighted switch arm connected to said primer and initially held to said pin by said other fusible material, said switch arm being movable, by centrifugal force, into engagement with said stationary contact. to connect said primer across said electrical source when said slug of fusible material and said other fusible material on said pin are melted by heat produced by said squib when saidsquib is ignited.

3. A self-destruction switching mechanism, comprising, an electrical source, and explosive means connected across said electrical source, thermal means ignitable by said electrical source, a heat conductive pin associated with said thermal means to receive heat therefrom, a stationary contact in heat conductive association with said thermal means, said contact being electrically connected to said electrical source, a slug of fusible material held by said stationary contact, other fusible material, and a weighted switch arm connected to said explosive means and initially held to said pin by said other fusible material, said switch arm being movable, by centrifugal force, into engagement with said contact to connect said explosive means across said electrical source when said slug of fusible material and said other fusible material on said pin are melted by heat produced when said ignitable means are operated.

4. In an electrically operated projectile fuze having a source of electrical energy and an explosive primer means connectable across said electrical source, the combination with a self-destruction switching mechanism including a thermal squib means ignitable by said electrical source, a heat conductive element associated with said squib means to receive heat therefrom, a stationary contact in heat conductive association with said squib means, said contact being electrically connected to said electrical source, a slug of fusible material held by said contact, other fusible material, and a weighted switch arm connected to said primer means and initially held to said element by said other fusible material, said switch arm being movable, by centrifugal force, into engagement with said contact to connect said primer means across said electrical source when said slug of fusible material and said other fusible material on said element are melted by heat produced by said squib means upon ignition thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,498,032 Dell et al. Feb. 21, 1950 FOREIGN PATENTS 585,791 Great Britain Feb. 25, 1947 

